NAC445A.6719. Cross-connections and backflow: Assemblies for prevention of backflow.

     1. Each service connection must have an assembly for the prevention of backflow, of a type that is commensurate with the degree of hazard that exists on the property of the customer of a public water system. Except as otherwise provided in NAC 445A.67185 to 445A.67255, inclusive, the assembly may consist of any one of the following, as listed in the order of least to most protection:

     (a) A double check valve assembly.

     (b) A reduced pressure principle assembly.

     (c) An air gap.

     2. A reduced pressure principle assembly may be substituted for a double check valve assembly, and an air gap may be substituted for a reduced pressure principle assembly.

     3. With the approval of the supplier of water:

     (a) A double check detector check assembly may be substituted for a double check valve assembly; and

     (b) A reduced pressure detector assembly may be substituted for a reduced pressure principle assembly.

     4. A double check valve assembly or double check detector check assembly may be used only for protection against pollution.

     5. A reduced pressure principle assembly or reduced pressure detector assembly may be used for protection against pollution or contamination, but a reduced pressure principle assembly must not be used for protection against sewage or reclaimed wastewater.

     6. An assembly for the prevention of backflow must not be composed solely of a single check valve.

     (Added to NAC by Bd. of Health, eff. 2-20-97)